no output waveform after simulating in quartus II simulator.

Hi..I am new to quartus and I am currently working on an 32 bit addition/subtractor block. First I thought that my .bdf files are erroneous because whenever I input a .vwf file(containing the input output nodes of my circuit) and simulate it with quartus simulator--->timing simulation; the simulator displays only a window that exits instantly . The bigger problem is that it doesn't display any output waveform. Out of curiosity I design a simpler circuit....an ordinary AND gate.:) and created the corresponding inputs in the simulation waveform editor, but the same problem arised....... Lastly I noticed that simulator produces a ****.vwf.temp file.